Measuring apparatus.



G. H. GIBSON.

MEASURING APPARATUS.

APPLICATION FILED MAR-15,1913.

1,202,053. Patented Oct. 24,1916.

avwum coz UNITED F STATES PATENT o FIoE.

' GEORGE H. GIBSON, F MON TCLAIR, NEW JERSEY.

mEAsuEme APPARATUS;

To all whom it may concern:

Be it known that I, GEORGE GmsoN, a citizen'of the United States ofAmerica, re-

siding in Montclair, in the county of Essex and State of New Jersey,have invented a certain new and useful Improvement, in MeasuringApparatus, of which the -following is a true and exact description,reference being had to the accompanying drawings, which form a partthereof. I

My present invention relates to means for measuringflowing liquid, andthe primary object of my invention is to provide efl ective andrelatively simple and inexpensive means adapted to measure boiler feedwater and especially pre-heated boiler feed water as it is passed to theboiler, and for measuring other flowing liquids where analogous flowandfpressure conditions prevail.

More specifically, the object of my inv';e'n-.

tion is to provide means whereby aVenturi t be meter, a Pitot-tubemeasuring device,-or 0 her analogous means, may be employed underconditions such as are experienced when the liquid to be measured iswater passing with a relatively low velocity head from the hot well of acondenser or from an open feed water heater to a boiler feed pumplocated at a level but slightly below boiler, the fluctuations in Howdue to .the-

the lex el of the Water in the hot well or heater. v i

. Heretofore it has been found impracticable, or at leastunsatisfactory, toplace a Venturi tube meter in a boiler feed line. Whensuch a meter, is placed in the boiler feed line between the usualreciprocating or other displacement feed pump and the operation ofthe'pump tend to materially reduce the accuracy of the measurements obtained. To minimize the injurious conse- "quences of such fluctuations,it has been i proposed to provide the pump'with an air cushioningcylinder. Such a chamber "must 'be of considerable size to make iteffective at all, and in many cases it has been found necessary tosupply compressed air to the chamber either continuously or at. frequentintervals to make up forthe ,loss of air which is continuallylbeingabsorbed'by the water pumped; In-. -consequence, the use in connectionwith a boiler fee pump of an air cushioning chamber of sufficient sizeto be effective is generally regarded as impracticable. Furthermore, aVenturi tube Specification of Letters Patent.

' Patented Oct. 24, 1916.

Application filed March 15, 1918. Serial No. 754,460.

referred to above, and in some respects even more serious. Thefluctuations in flow are, of course, as bad on one side of the pump ason the other.

ratio Venturi tube meter locatedon the suction side of the pump there isa marked tendency of the stream through the meter to break at the loWpressure zone on the suction stroke of the pump, especially when theliquid is heated .toa temperature at which its vapor tension is butlittle below the hydrostatic pressure in the high pres' sure zone of themeter. The Pitot tube measuring device like the Venturi meter isadversely aflected by fluctuations in flow, although with it there isnot the same tendency for the liquid stream to break under certainconditions as is experienced with the Venturi meter. The Pitot tubevmeasuring device is in general, however, a less satis' factorymeasuring device than the Venturi tube meter for service of thecharacter men- -tibned,.because-it ismore apt to clog up and gives,withithe usual velocities of water in feed pipes, a much smallerdiflerenti'al pressure frc-m which the'rate of flow is .deter-Furthermore with a high mined. Inconsequence of the objections at;tending the use of Venturi tube meters and Pitot tube measuring devicesfor measuring boiler feed water and especially pre-heated' boiler feedwater, it has become a common practice where itis desired to measurethis water, to pass the water through a weir- ,chamberand to determinethe rate of flow from the varying accumulation of water on the supplyside of the weir over which it flows. Weir measuring apparatus operatessatisfactorily for this purpose, but is open to theiobjecticnthat it isbulky and-takes m ma deal 'ofspace which'is sometimes -very' valuable,and the apparatus is relatively' expensive.

To overcome the objections which have I hitherto prevented thesuccessful-use of a- Venturi tube meter or a. Pitot tube measur ingdevice for measuring boiler feed water, I

place a measuring pipe section, which may be eithera Venturi tube or aplain pipe section with Pitot tube connections thereto, in the boilerfeed line, and connect this measuring section at each end to acorrespondingly located flow equalizing reservoinand provide means formaintaining the upper portions of said reservoirs filled with gaseousfluid at the same pressure; With this arrangement. the rate of flowthrough the measuring pipe section will be in dir ct response to thegravity head due to the ifierence in height of liquid levels in the tworeservoirsand will be only indirectly'afiected by the operation ofthe-pump. For instance, where the boiler feed pump draws water from thehot well of a condenser or from an open feed water heater, the flowequalizing.

reservoirat one end of the measuring pipe section may be the hot well oropen feed water heater, and at the other end, a stand pipe interposedbetween the measuring .section and the suction inlet of the pump, andpreferably located immediately adjacent the latter. In this arrangementthe vapor space of the hot well or open feed water heater should beconnected to the upper end of the stand pipe by a vapor equalizingconnection. With this arrangement the pump draws water in a more or lessirregular manner from the stand pipe or reservoir. The water level inthe latter rises and falls with the pulsations in flow through the pump,but the flow into the reservoir is to a large extent free from-themomentary fluctuations due to the operation of the pump and approximatesthe average rate of flow required to supply the amount of waterwithdrawn from the reservoir by the pump. The equalization of the flowthrough the meter resulting from the use of the pressure'equalizingreservoir substantially reduces the velocity head in the meter necessaryfor satisfactory operation.

This means in practice that the water level' in the heater may besubstantially lower relative to the suction inlet of the pump than wouldotherwise be required. To enable me to still further reduce the velocityhead required in a Pitot tube measuring device or Venturi tube meteremployed, and thus minimize the frictional loss of head which wouldoccur if the Pitot tube were placed in a smaller pipe or if a higher.ratio Venturi tube meter were employed, I preferably employ inconnection with either form of' measuring device a, differentialpressure measuring means which is adapted to magnify the actualdiiference in pressure existing between the low and high pressure pointsof the Venturi tube meter or the Pitot tube measuring device.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and formingapart of this specification.

For a better understanding of the invention,

however, and of the advantages possessed'by it, reference should be hadto the accompanymg drawings and descriptive matter in which I haveillustrated and described forms in which-my inventionmay be used.

Ofthe drawings: Figure 1 is a somewhat diagrammatic elevation partlybroken away and in se'ctionof a boiler feed water system.

in whicha Venturi tube meter is arranged in accordance with my presentinvention.

Fig. 2 is a partly sectionalelevation of a portion of a boiler feedwater system which may be similar to that shown'in Fig. 1, except that aPitot .tube measuring device is employed in place of a Venturi tubemeter.

In the drawings A represents an open feed water heater of well knowntype, A being .the steam supply pipe, A the water supply pipe, and A thevent pipe connection thereto. The hot Water is drawn from the heaterthrough a pipe B by a reciprocating boiler feed pump C located at alevel which needs to be but slightly below the normal water level in thefeed water heater. The pipe B instead of leading directly to the suctioninlet of the pump C opens into a stand, pipe or reservoir D, which isalso connected to .the suction inlet of the pump. Advantageously theconnection between the stand pipe and pump is as short as isconveniently pos- Sible.

E represents a vapor equalizing pipe connection between the top of theheater A and the top of the stand pipe D.

Included in the pipe B at any convenient place along the length of thelatter is a Venturi tube section F which ordinarily-and preferably is alow ratio tube; that is, one in which the difference between the crosssecand the low pressure zone F is comparatively small. Pipes Gr and Hrun from the zones F and F of the Venturi .tube section F to thechambers I and I respectively, of

' phragm J The chamber I receives a fluid under -the proper pressure tobalance the difl'erential-of the fluid pressures acting on the oppositesides of theidiaphragm J. This pressure fluid'is supplied by the pipe Kwhich includes a flow reducing device in the form of a plate L formedwitha small restricted orifice L through which only a relatively tionalareas of the high pressure zone F slow flow ofthe .pressure fluid cantake place. The pipe K leads from any suitable source of fluid underpressure exceedlng the maximum balanclng pressure required 111 thechamber I. Thepressure fluid employed may be steam, water, compressedair or the latter is formed with a vent port M opening M being closed)quickly builds up the pressure in the chamber I to the required to theatmosphere and controlled by a ball valve N which normally tends to seatagainst and close the, port M. This port is coaxial with the diaphragmsJ, J" and J and the rod J connecting these diaphragms at their centersis formed with an extension entering the port -M and arranged to liftthe valve N off its seat on a slight upward movement of the diaphragmsand to permit the valve to seat on a slight downward movement of thediaphragms.

\V'th the arrangement vdescribed it will be apparent that when thepressure in the balancing chamber I becomes momentarily too high thevalve N is lifted off its seat thus permitting the pressure fluid toescape through the port M until the desired equilibrium isreestablished. -VVl1en'the pressure in the balancing chamber becomesmomentarily too low the constant influx of pressure fluid through-therestricted port L (port amount. A pressure is thus automaticallymaintained in the chamber I which is that required to balance thedifferential of the forces acting on the opposite sides of the diaphragmJ. It will be apparent of course that the operation of tne apparatus ispractically independent of the actual pressure in the pipe K at theinlet side of the port L provided only that this pressure exceeds themaximum pressure required in .the balancing chamber I To obtain a recordof the balancing pressure in the chamber I and consequently of the rateofflow through the pipe B, the chamber 1 is connected as by the pipe Nto a U tube 0 which is partly filled with mercury or some other suitablefluid. The U tube 0 opens at the upper end of one leg into a floatchamber O receivinga float P which carries a pencil or other device Pformak-' ing a recordon the clock driven drum Q. The other leg 9 of theU tube, to the upper end of which the pipe N is connected, is preferablyof such varying cross section with reference to the operatingcharacteristics of the Yenturi ttibe meter or'other measuring deviceemployed that the height of liquid level in the float chamber 0 whichmay be cylindrical will vary proportionally with the rate of flowthrough the meter. As is well known, the difference between the sides atthe zones F and F of the meter shown, while varying in accordance, withchanges in the rate of flow through. the

meter, is not a linear function of the rate of anism and the U tuberecording and ,recti-. fying instrument shown and'described are notspecifically claimed herein, but are disclosed in detail and claimed inmy prior ap- The differential pressure balancing mechplication SerialNo. 716,803, filed August 24, i

1912. It is not essential to the use of the invention claimed hereinthat the particular type of differential pressure measuring andrecording apparatus shown beeinployed. I

consider it highlyv desirable, however, to employ a differentialpressure measuring apparatus which, like that shown, willmultiply theactual pressure differential existing in the Venturi tube meter or othervelocity meter employed, and the particular form of pressure balancingand recording mechanisnr illustrated I consider the best of all forms ofmechanism for this purpose now known tome. a

With the apparatus described it will be apparent that the stand pipe orflow equalizing reservoir D will absorb practically all of the momentaryfluctuations in flow due tothe operation 011 the reciprocating pump- Cso that the flow through the pipe B and meter tube section F will befairly steady. It will be apparent,-more'over, that'an'increase in thelength of the pipe B will add -to, rather than diminish, theefi'ectiveness of the apparatus, for thegreater the inertia of thestream flowing through the pipe B i the pressure measuring and recordingap paratus, whichmay be similar to that shown in Fig. 1, are connectedrespectively to the 1.15

Pitot tube R and directly to the pipe B at any convenient place in theneighborhood of the Pitot tube R. I As already explained, much the sameadvantages are obtained with the Pitot tube as with the Venturitubemeter when used in accordance with the.

present invention. In general, however, I

consider the Venturi tube meter'preferable j 7 to the Pitot tubemeasuring device for service-of this character. Z f

"Whilein accordance with theprovisions of the statutes, I- haveillustrated and described the best forms of my invention now known tome, it will be apparent to those skilled in the art that changes may bemade in the form of'the apparatus disclosed with 130 tween which theresistance to flow creates a differential pressure corresponding to therate of flow and of. suflicient magnitude to permit the rate of flow tobe determined therefrom.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is: Y a r 1. The combination with aliquid flowline and a pump forcausing liquid to flow therethrough, said flow linecomprising a measur ing pipesection and a flow equalizing reservoirinterposed between one end of the measuringsection and the pump, asecond flow equalizing reservoir to which the other end of said sectionis connected, means for maintainingthe upper portions of said reservoirsfilled with gaseous fluid at the same pressure whereby the rate of flowthrough said section will be responsive 'to the gravity head due to thedifference in liquid levels in the two reservoirs, and means fordetermining the rate of flow through said measuring section from thedifference in pressure created at separated points in said pipe by theflow therethrough. v 7

2. The combination with a liquid flow line and a pump for causing liquidto flow therethrough, said flow line comprising a measuring pipe sectionand aflow equalizing reservoir interposed between one end of themeasuring section and the pump, a second flow equalizing-reservoir. towhich the other end of said section is connected, means for maintainingthe upper portions of said reservoirs filled with gaseous fluid at thesame pressure whereby the rate of flow through said section will beresponsive to the gravity head due to the difference in liquid levelsin'the two reservoirs, and means for magnifying the difference inpressure created at separated points in said pipe by the flow throughwhich said pipe is connected to the suction inlet of the pump and meansfor maintaining the upper portions of said reservoirs ,filled withgaseous fluid at the same pressure.

4. The combination with a closed cham- 7 her, a pipe and'a- .pump fordrawing liquid through the pipe from said chamber, the latter having itssurface level but little above the suction inlet of the pump, said pipeincluding means for creating a difference in pressure at separatedpoints corresponding to the rate of flow through the pipe, of means formagnifying this pressure differential and for determining the, rate offlow through the pipe therefrom, and a flow equalizing chamber extendinghigher than the surface level of the liquidvin said closed chamberthrough which said pipe is connected to the suction inlet of the pump,and a vapor equalizing pipe connecting the vapor spaces of saidchambers.

5. The combination with a source of liquid, a pipe and a pump fordrawing liquid through the pipe from said source, the latter having itssurface level but little above the suction inlet of the pump, said pipeincluding means for creating a difference in pressure at separatedpoints corresponding to the rate of flow through the pipe, of means formagnifying this pressure diflerential and for determining the rate offlow through the pipe therefrom, a

flow equalizing chamber through which said pipe isconnected to thesuction inletof the pump, and means for maintaining gaseous fluid in theupper end of said chamber under the same pressure as that acting uponthe,

surface level of said liquid source. r

' GEORGE H. GIBSON.

Witnesses: I f

J. RALPH GIBSON, EUGENE L. LARKIN.

